0:00

Now let's turn to the footprints that may be left behind.

0:04

Particularly with regard to the bone.

0:09

These can be classified as bone bruises.

0:13

Osteochondral fractures are sometimes fractures isolated

0:17

to the articular cartilage, avulsion fractures, uh,

0:21

or evulsion injuries.

0:23

We've already kind of commented on the typical footprints

0:28

that are associated with many tears of the ACL,

0:31

particularly those with flexion valgus and internal

0:36

or external rotation of the tibia.

0:40

We often see these sort, uh, this sort

0:43

of distribution on the medial

0:45

and lateral side, much more commonly on the lateral side.

0:50

And typically, again, there's an offset between

0:52

where we see the lateral or see the femoral problems

0:56

and where we see the tibial problems.

0:59

It suggested that the offset is less on the medial side

1:03

than it is on the lateral side in general.

1:06

So these are classic bone bruises

1:11

or fractures, the classic

1:13

distribution more commonly on the lateral side than

1:16

on the medial side.

1:18

And I've already gone through these particular slides

1:21

or one similar to them to show you

1:24

what osteochondral fractures look like.

1:27

A deep notch. This is the lateral condylar patella.

1:31

So is a long notch

1:33

or a double notch, particularly in the immature skeleton.

1:37

And I've talked it also about the wrinkled tibia,

1:41

an osteochondral fracture in the posterior aspect

1:44

of the lateral tibial plateau.

1:47

Let's turn our attention now to evulsion fractures.

1:51

And Eric Chang actually showed an example of a problem

1:54

that involved the semimembranosus tendon.

1:58

And we reported years ago, actually,

2:01

1999 when I was 10 years old, a radiologist.

2:05

We reported that when you saw avulsion fractures involving

2:10

any of the tendonous arms,

2:12

but particularly the direct arm, okay,

2:15

the direct tenderness arm,

2:17

when you saw an avulsion fracture,

2:19

there was a very high risk of tears

2:22

of the anterior cruciate ligament.

2:24

And at the time we reported this, I had seen no exceptions

2:28

to that rule.

2:29

Now I had, but still these are images taken from that paper.

2:34

If you see an avulsion back here related

2:37

to the semimembranosus, there is a high likelihood

2:42

that there is tearing of the anterior cruciate ligament.

2:47

The second site of avulsion fracture is indeed the

2:51

tibial, uh, eminence,

2:53

the intercondylar eminence of the tibia.

2:56

And here there is a classification

2:58

System of Myers

3:00

and McKeever that will, it's illustrated here.

3:03

That depends upon the degree of elevation

3:07

of the intercondylar eminence and whether

3:10

or not it is rotated by showing an example of

3:13

what would be called probably a three a, uh,

3:17

avulsion fracture of the intercondylar eminence

3:20

where there is a gap between it.

3:23

Okay? And the sub uh, uh, bone.

3:27

All right, so this would be the classic evulsion fracture.

3:31

And I wanted to include this to remind you

3:33

that if you are dealing with a higher grade injury

3:37

with more displacement or displacement

3:39

and rotation, you gotta look beneath the displaced bone

3:43

because there may be entrapment of soft tissue structures

3:48

beneath that particular avulsion fracture.

3:51

It may be the anterior horn of the medial meniscus.

3:55

It can be the anterior horn of the lateral meniscus.

3:58

It can be that anterior transverse

4:01

meniscal meniscal ligament.

4:04

I show you this particular case.

4:05

We used it on a film panel

4:07

for the International Skeletal Society.

4:10

Here is a displaced evulsion

4:12

fracture involving a large port part

4:15

of the intercondylar eminence

4:17

and the arrows pointing to an entrap,

4:20

medial meniscus anterior horn beneath the displaced bone.

4:25

Now the third UL ocean fracture that occurs

4:28

with ACL pairs is the sigon fracture.

4:32

Everyone agrees about that.

4:33

Typically related to ary anterolateral rotary instability,

4:38

where the disagreement is what is the structure

4:42

that pulls off the piece of bone

4:44

that characterizes a sigon fracture for many, many years.

4:49

We suggested it was the lateral mid capsular ligament.

4:52

This is what that ligament looks like here

4:55

in the coronal section.

4:57

You can see that there is a meniscal femoral

5:00

and a meniscal tibial capsular ligament.

5:03

And indeed this is

5:05

where it is located in a transverse image.

5:07

Here is the fibular collateral ligament nearby.

5:11

So for many, many years, this was the cause

5:14

of the sigon fracture.

5:16

Now, I've listed some of the other things

5:18

that have been emphasized.

5:20

Portions of the ileo tibial tract may attach

5:24

to the lateral rim of the tibia.

5:26

There may be an oblique band

5:28

of the fibular collateral ligament or,

5:31

or maybe even some sort of accessory muscle tissue.

5:35

But the one that has gained the most significance

5:38

and the one that Eric mentioned in one of his cases

5:42

is the antral lateral ligament of the knee.

5:45

And this is a ligament that has been so-called

5:49

recently discovered.

5:51

All right? And it made headlines. All right. We found a new

5:56

Structure in the knee,

5:57

and this is what it looked like running from the area

6:00

of the lateral femoral epicondyle in front

6:03

of the fibular collateral ligament to this particular ridge

6:07

or area involving the proximal tibia.

6:10

And this is what an injury to it might look like.

6:14

And so a lot of people said, yeah, this is the critical

6:18

stabilizer particularly to internal rotation of the tibia,

6:23

and it is this particular ligament that may be responsible

6:26

for the CI fracture.

6:28

Now, I can tell you that not everyone agrees with this,

6:31

and many of us, including myself,

6:33

believe this particular ligament looks almost identical

6:37

or is identical to the lateral mid capsular ligament

6:41

of the knee described years ago.

6:44

But it has gotten a lot of press.

6:48

Now, this is what an acute CI fracture looks like.

6:52

All right? And by the way, often you won't see a lot

6:56

of marrow edema near it on the fluid sensitive sequences.

6:59

So you may miss it.

7:01

It may be very small

7:02

and you may see it better on conventional radiography.

7:06

This is what a chronic sigon fracture looks like described

7:11

by two of our fellows years ago,

7:14

and we call it the Bosch Bach bump,

7:16

although maybe some people call it the Bach bsch

7:19

bump, right?

7:21

It is an expressions that occurs from the lateral aspect

7:24

of the tibia slightly below the joint line.

7:27

Now, in some persons, normal persons,

7:30

there's a slight bump there.

7:31

In others you don't see something this large. Okay?

7:35

So when you see that it probably represents a chronic sigon

7:39

fracture, I cannot tell you its pathogenesis

7:43

'cause I have not followed persons with this stage

7:46

to this stage to prove it relates to fusion

7:49

of the uls bone fragment.

7:53

There is a soft tissue sagon injury in which you see a

7:57

contusion or marrow edema, like changes involving the area

8:02

that we normally would see

8:04

or abnormally would see a sagon fracture.

8:07

There's no fracture here.

8:09

There's just altered marrow signal, okay?

8:12

This is called a soft tissue SAG injury, right?

8:16

It's associated with tears of the ACL

8:18

as in this particular case,

8:21

and a variety of injuries

8:22

to the lateral supporting structures of the knee.

8:25

So this is a soft tissue cigar injury.